RFI-EMI-GUY - I discovered (thanks to the radio in question) that my LED outdoor lighting is very, very noisy. So noisy that I had to turn them off at the panel so I could play with the radio. Anything I can do, shy of replacing all the fixtures with FCC approved units, to mitigate the interference? I'm upgrading the cheapo Radio Shack RG58 coax with slightly better RG8X this week, and I'm hoping that helps a little.
Seeing as you have tracked the RFI to your own lights, your battle is half over.
These first two recommendations may help with respect to common mode interference traveling on the earth ground to the antenna.
1) The antenna system needs to be grounded per NEC. That means it should be grounded to the same ground rod as your electrical panel. Likewise the radio and power supply should be bonded to this point. Motorola R56 is a helpful guide to grounding and bonding.
2) Improving the coax is always good, however the % of shielding of the coax is important. Compare specs of what you are buying and use good connectors and a proper lightning arrestor. I have been fortunate to find double shielded teflon insulated RG8 type coax for my equipment. It was surplus 400 feet for $75. I doubt that bargain exists today. It was 50 ohm plenum cable for networks. Probably surplused from a Los Alamos type govt project.
3) You LED lighting is probably junk. The manufacturers sometimes do not meet FCC requirements for residential installations. Good luck weeding out commercial lighting products (worst) from residential (better) at your home improvement store.
Also the specs are so weak that while you can buy compliant bulbs that won't bother a neighbor, those bulbs will cause you interference in your own home.
4) You might try this list for recommended bulbs:
https://www.liftmaster.com/catalogr.../tucmanuals/led bulb compatibility_011714.pdf
More from FCC on the problem:
https://apps.fcc.gov/eas/comments/GetPublishedDocument.html?id=407&tn=269260
5) If better LED bulbs don't fix the problem you can try some ferrite chokes (or filters) on the leads going to the bulb socket. There are plenty of Ham radio articles about the use of these chokes. Experimentation is in order.
6) As mentioned by another, this noise could be traveling through the wiring of the house, especially if you are in a locale that permits ROMEX, your entire house wiring may be an antenna. So chokes at the power cord for the power supply are a potential fix. You don't mention your power supply, it is probably a switcher and those have their own sort of goblins. I have used an AC power line filter on some of my sensitive equipment. They can be obtained surplus. CORCOM is a popular make. Usually a sealed metal can with a pair of "PI" filters. They have terminals for passing through the line and load terminals and have a third ground terminal.